The estimated effect for each variable and the interactions
between the variables were determined and are reported
in Table 5. Both variables are relevant to tannase
production at a 95% confidence level. The correlation
analysis has shown that the MgSO4 interaction versus the
agitation rate and the MgSO4 quadratic term were not
statistically significant. The agitation rate quadratic term
and both linear terms are significant, which affects the
curvature in the response surface plot. The analyses of the results show that the deviations were low in the desirable
range where the activity value was high.